Sheet stacking apparatus

1. A sheet stacking apparatus, comprising:

a conveyance unit configured to convey a sheet;

a stacking unit on which the sheet conveyed by the conveyance unit is stacked, the stacking unit inclined downward in a conveyance direction in which the conveyance unit conveys the sheet and comprising a first region and a second region, the second region being located downstream of the first region in the conveyance direction;

a pressing portion having a pressing section configured to press the sheet on the first region, a first portion being a most downstream portion of the pressing section in the conveyance direction; and

a guide portion configured to guide the sheet conveyed by the conveyance unit over a preceding sheet placed on the second region, the preceding sheet having been conveyed by the conveyance unit before the sheet, an upstream edge, in the conveyance direction, of the preceding sheet being located in the second region, a second portion being a most downstream portion of the guide portion in the conveyance direction, the second portion being configured to guide the sheet conveyed by the conveyance unit over the preceding sheet placed on the second region,

wherein in a case where the sheet is not on the stacking unit, the first portion is located upstream, in the conveyance direction, of the second portion.

2. A sheet stacking apparatus according to claim 1 ,

wherein the guide portion is arranged at the stacking unit.

3. A sheet stacking apparatus according to claim 2 ,

wherein the guide portion is arranged at the first region.

4. A sheet stacking apparatus according to claim 1 , further comprising a downstream pressing portion configured to press the sheet placed on the second region,

wherein the downstream pressing portion has a downstream pressing section configured to press the sheet on the stacking unit, and

wherein a third portion which is a most downstream portion of the downstream pressing section in the conveyance direction is located downstream of the second portion in the conveyance direction.

5. A sheet stacking apparatus according to claim 4 ,

wherein the pressing portion has a pivot supporting point located above the stacking unit and upstream of the second portion in the conveyance direction.

6. A sheet stacking apparatus according to claim 5 ,

wherein the pressing portion is directed toward the guide portion so as to guide the sheet conveyed by the conveyance unit toward the guide portion.

7. A sheet stacking apparatus according to claim 5 ,

wherein the pressing portion comprises:

a coupling shaft supporting point arranged between a lower end on a side of the stacking unit and the pivot supporting point;

a first pressing portion provided between the lower end and the coupling shaft supporting point; and

a second pressing portion provided between the coupling shaft supporting point and the pivot supporting point,

wherein the first pressing portion is coupled to the second pressing portion at the coupling shaft supporting point in a pivotable manner, and

wherein the first pressing portion and the second pressing portion are configured to press, at different heights, the sheet placed on the second portion.

8. A sheet stacking apparatus according to claim 1 , wherein the guide portion is inclined downward in the conveyance direction.

9. A sheet stacking apparatus according to claim 4 , wherein the downstream pressing portion is operable independently of the pressing portion.

10. A sheet stacking apparatus according to claim 1 , further comprising a folding portion configured to fold the sheet,

wherein the sheet folded by the folding portion is conveyed to the stacking unit by the conveyance unit.

11. A sheet stacking apparatus according to claim 1 , wherein a step is provided between the second portion and the second region.